Chemical analysis : a tool for differentiation between human and nonhuman bones

Abstract

Forensic anthropologists play an important role in the identification or exclusion of human remains recovered amongst animal remains and environmental ruins. Accurate separation techniques are needed as small animal bone fragments can easily be mistaken for human neonatal or infant remains. Distinguishing between human and animal bones is easily done if the remains found contain distinctive gross morphological features related to the specific species involved. In the absence of these anatomical characteristics different methods have to be explored to enable the investigator to accurately determine the origin of the remains in question. The aim of this study was therefore to compare the chemical composition of human and nonhuman bones that could aid in separation of skeletal material. As part of a larger MSc, attention is also given to the analyses of human and animal bones. The observed group consisted of dry bone samples removed from the anterior midshaft of four (4) tibiae collected from each of the following herbivorous, carnivorous and omnivorous species: adult sheep (Ovis aries), pigs (Sus scrofa domestica), dogs (Canis lupus familiaris) and humans (Homo sapiens sapiens). The average elemental composition of each of the individual species was measured using a scanning electron microscope (SEM) fitted with an electron dispersive spectrometer (EDS) system. Previous research has indicated that the inorganic composition of bone consists of phosphate (±50%), calcium (±35%), carbonate (±6-7%), citrate, nitrate, sodium, magnesium, fluoride and strontium. The results of this study confirm these findings, but indicate variable percentages in, for example, the strontium content of sheep (0.01%, SD±0.05), pigs (0%), dogs (0.01%, SD±0.02) and humans (0.08%, SD±0.24). These results may prove useful in the exclusion of human bones among animal remains and vice versa.